The invention relates to the field polarization mode dispersion, and in particular to a device that can compensate and emulate within a large frequency range.
As the bit rate of a single channel increases, a compensator that cancels first order polarization mode dispersion (PMD) is no longer sufficient since higher order PMD dominates the signal's degradation. Typical higher order PMD compensators are multistage devices that have many degrees of freedom. If the compensation scheme relies on feedback loops, the complexity involved in searching the optimum of many parameters may hinder the development of a fast and stable compensator. Thus, feed-forward approach to PMD compensation appears more feasible when higher order PMD compensation need to be addressed. Recently, several schemes of real-time PMD estimation technique had been proposed.
Previous approaches to all-frequency PMD compensation aim to generate the inverse of transmission fiber's Jones matrix U(ω) for all frequencies. Most of these efforts concentrate on the synthesis of filter response to approximate this unitary matrix, U(ω). In one architecture, it describes using all-pass filters to invert the measured Jones matrix U(ω) approximately. The approach is very promising as it can be compactly integrated using planar waveguides.